1. Field of the Invention
The present invention generally relates to a thinner composition and a method of removing a photoresist using the thinner composition. More particularly, the present invention generally relates to a thinner composition having improved solubility properties and a method of efficiently removing an edge bead relative to various photoresist or anti-reflective materials using the thinner composition.
A claim of priority is made to Korean Patent Application No. 2004-8678 filed on Feb. 10, 2004, the contents of which are incorporated by reference in their entirety.
2. Description of the Related Art
Semiconductor devices having a high degree of integration and rapid response speed are desired as information processing apparatuses continue to develop. Hence, the technology for manufacturing semiconductor devices has developed to improve the degree of integration, reliability, and response speeds of the semiconductor devices.
To manufacture a conventional microcircuit, for example, impurities are precisely implanted into regions on a silicon substrate, and then the impurity regions are electrically connected to each other to form a very large scale integration (VLSI) circuit. A photolithography process is used to form patterns, which define the impurity regions. After forming a photoresist film on the substrate, the photoresist film is exposed to light such as an ultra violet ray, an e-beam, or an X-ray. The photoresist film is developed and then exposed portions on the substrate are removed.
Conventionally, a photoresist is coated while a substrate is rotated such as a spin coating process; the photoresist evenly coats on an edge and backside of the substrate. However, the photoresist coated on the edge or the backside of the substrate generates particles known as an edge bead, which may cause process failure in subsequent processes such as an etching process or an ion implanting process. Therefore, an edge bead removal (EBR) process using a thinner composition is generally required to remove the unwanted particles from the substrate.
Sometimes, a failure of a photoresist pattern may occur during a photolithography process. When the failure of the photoresist pattern occurs, a reworking process is performed to remove the failed photoresist pattern from the substrate. The reworking process is used to save the substrate.
As patterns on semiconductor devices become finer, photoresist compositions have been developed by an I-line ray or a G-line ray. A photoresist composition generally includes a novolak resin as the main ingredient. In addition, an amplified photoresist that is sensitive to an excimer laser or an extreme ultraviolet ray has been used to manufacture semiconductor devices. Thus, a thinner composition having good solubility relative to these types of photoresist is required.
U.S. Pat. No. 5,866,305 discloses, for example, a thinner composition containing ethyl lactate and ethyl 3-ethoxy propionate, and also discloses another thinner composition containing ethyl lactate, ethyl 3-ethoxy propionate, and gamma-butyro lactone. Although widely used, the above-mentioned thinner compositions have poor solubility relative to certain photoresists such as amplified photoresist. In addition, the thinner compositions are relatively expensive due to ethyl 3-ethoxy propionate, which is used as the main ingredient. Further, the thinner composition has poor solubility and EBR characteristics relative to photoresist using an argon fluoride (ArF) laser.
U.S. Pat. No. 6,159,646 discloses another conventional thinner composition containing ethyl lactate and gamma-butyro lactone; a thinner composition containing ethyl lactate, ethyl 3-ethoxy propionate, and gamma-butyro lactone; and, a thinner composition containing ethyl lactate and ethyl 3-ethoxy propionate. The cost to prepare thinner compositions containing ethyl 3-ethoxy propionate and gamma-butyro lactone is substantially high. These thinner compositions also have substantially poor solubility relative to photoresists using an ArF laser.
The above-described conventional thinner compositions are employed in reworking processes and in EBR processes; however, the thinner compositions are inappropriate for both processes.
A thinner composition containing an acetic acid ester compound, gamma-butyro lactone, and a non-acetate type ester, as disclosed in Korean Patent Laid Open Publication No. 2003-51129, is effective in removing photoresist using an I-line ray, a G-line ray, and krypton fluoride laser in a reworking process or an EBR process. However, the thinner composition has poor solubility relative to a photoresist using an ArF laser. In addition, the thinner composition has poor EBR characteristics. A thinner composition having good solubility relative to THE photoresist exposed to an ArF laser, which effectively removes unwanted photoresist in an EBR process, and is effective in a reworking process is required.